Stage Controller

i saw in electrical panel of hvac quipment somthing called temperature controller and in the notes of the?

drawing and in the notes of the drawing "temperature controller 2 cooling stage only"
what this temperature controller and what is the relation between this and Hvac equipment like Fans and chillers cooling towers ...etc.

Two stage means that it has two levels of cooling. Low and high.

This is typically be 50% of total capacity and 100% of total capacity but can vary slightly depending on the equipment being controlled.